How low can you go?

.... On Sundays the boyfriend and I walk to the station, it’s good exercise and we have some time to chat. Last Sunday we were walking and I was rolling my bag through some left-over snow. I honestly thought it was the snow which made my bag feel so much heavier with every step. The boyfriend took over the bag and we continued our walk. With about 300 meters to go I told him that I needed to measure at the station because I was going low..... ns trein